The Δ122p53 allele is associated with a reduced life span and altered tumor spectrum compared with the p53 null allele. (A) Mice of various genotypes were observed for 600 days and Kaplan-Meier curves plotted. (B) Relative frequencies of tumors identified by histopathologic examination are displayed as pie charts. n = cohort size − mice censored because of postnatal exencephaly.